ConstantTransformer (Commons Collections 3.2.2 API)

java.lang.Object
- org.apache.commons.collections.functors.ConstantTransformer

All Implemented Interfaces:

Serializable, Transformer
```
public class ConstantTransformer
extends Object
implements Transformer, Serializable
```
Transformer implementation that returns the same constant each time.
No check is made that the object is immutable. In general, only immutable objects should use the constant factory. Mutable objects should use the prototype factory.

Since:

Commons Collections 3.0

Version:

$Revision: 646777 $ $Date: 2008-04-10 14:33:15 +0200 (Thu, 10 Apr 2008) $

Author:

Stephen Colebourne

See Also:

Serialized Form

Field Summary

Fields
Modifier and Type Field Description

static Transformer NULL_INSTANCE
Returns null each time

Constructor Summary

Constructors
Constructor Description

ConstantTransformer(Object constantToReturn)
Constructor that performs no validation.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`Object`	`getConstant()`	Gets the constant.
`static Transformer`	`getInstance(Object constantToReturn)`	Transformer method that performs validation.
`Object`	`transform(Object input)`	Transforms the input by ignoring it and returning the stored constant instead.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - NULL_INSTANCE
```
public static final Transformer NULL_INSTANCE
```
    Returns null each time
- Constructor Detail
  - ConstantTransformer
```
public ConstantTransformer(Object constantToReturn)
```
    Constructor that performs no validation. Use getInstance if you want that.
    
    Parameters:
    
    constantToReturn - the constant to return each time
- Method Detail
  - getInstance
```
public static Transformer getInstance(Object constantToReturn)
```
    Transformer method that performs validation.
    
    Parameters:
    
    constantToReturn - the constant object to return each time in the factory
    
    Returns:
    
    the constant factory.
  - transform
```
public Object transform(Object input)
```
    Transforms the input by ignoring it and returning the stored constant instead.
    
    Specified by:
    
    transform in interface Transformer
    
    Parameters:
    
    input - the input object which is ignored
    
    Returns:
    
    the stored constant
  - getConstant
```
public Object getConstant()
```
    Gets the constant.
    
    Returns:
    
    the constant
    
    Since:
    
    Commons Collections 3.1